1. Field of the Invention
The present invention relates to fiber optic devices used for communication and other applications. More specifically, the present invention relates to planar lightwave circuits.
2. Description of the Related Art
As is well-known in the art, many optical circuits use optical guides: planar lightwave circuits constructed with patterned silicon-dioxide layers on a silicon substrate.
Planar lightwave circuits (PLCs) made of low-loss silica promise to make significant impact as they reach commercial viability. Indeed, silica-based planar lightwave circuits—passive optical waveguide strictures made using photolithographic techniques—comprise one of the most dynamic segments of the photonics field. Among their key virtues are extremely low propagation loss (0.01 dB/cm), excellent fiber coupling loss (0.1 dB for low index contrast waveguides), ease of defining complex structures such as Arrayed Waveguide Grating (AWGs) and Mach-Zehnder arrays using photolithographic fabrication processes, mode compatibility with optical fibers, and physical robustness. However, silica is a passive material with no electrically controlled phase shifting ability except for slow thermo-optic index modulation techniques.
In general, passive materials, previously used for routing and switching, offer low losses but suffer from low speeds and are not electrically responsive. Active materials, used for modulators and other devices, offer higher speeds but suffer from higher losses as well.
Consequently, a need exists in the art for a system and method for integrating low loss passive materials with active high speed electro-optic materials to make more sophisticated devices such as modulators, routers and switches using fabrication processes compatible with both passive and active materials.